Use of phosphorus-31 MR spectroscopy to monitor response to chemotherapy in non-Hodgkin lymphoma.

Two patients with non-Hodgkin lymphoma of the femur were examined with 31P magnetic resonance spectroscopy (MRS) and proton magnetic resonance imaging before and during treatment with chemotherapy. Prior to treatment, 31P MRS of the tumor showed that in comparison to normal skeletal muscle, phosphocreatine was reduced, and phosphomonoesters (PME) and phosphodiesters were elevated. The 31P spectrum became similar to that of normal muscle after 40 days of treatment in both cases. Following the initial dose of chemotherapy, an increase in PME relative to adenosine triphosphate was observed within 48 h in one patient. Magnetic resonance showed a change in the soft tissue component of both tumors and 6-12 months later there was no clinical evidence of any recurrence. Magnetic resonance spectroscopy with 31P may prove to be a sensitive technique for monitoring therapeutic response of tumors.